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Ricardo Torres avatar image
Ricardo Torres asked ·

VDB Volume Shader

Hello. I am wondering about the standard volume settings in C4DtoA. This image is an example of the issue I'm having with blockiness in the render. I create a VBD sequence with X-Particles and xpExplosia. The vortex was set to 0.7 in the solver so very decent resolution. I then exported the VBD xpExplosia cache to create the Arnold Volume. I changed the default scale of the volume to cm and change the z scale of the object to -1 so everything matches the size of my scene and the original xpExplosia object. Then, as recommended in the Arnold VBD volume documentation I scaled up the density and emission (fire and smoke) to 100 (because the object was reduced from meters to cm). The problem I am having is the blockiness you see in the emission. At first I thought it was my voxel size but the emission (and density) looks fine with out blockiness in other render engines (like Octane). Any suggestions on why this might be the case in Arnold? (that I prefer to use to render) Might there be an advance setting on the standard volume shader that I am missing?

volumesx-particlesopenvdb
volume.jpg (112.9 KiB)
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Peter Horvath avatar image
Peter Horvath answered ·

I'm not sure where the blockiness is coming from. If you can send me some frames from the exported VDB sequence, I'll take a look. I'm on vacation this week, so I'll react a bit slower, sorry about that.

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Peter Horvath avatar image
Peter Horvath answered ·

No worries, man. Try to change the Interpolation to tricubic in the volume shader under the Advanced section. It will be a bit slower, but should produce the better result. I still have to take a deeper look into the vdb file to be able to tell what's going on.

You mentioned it looks fine in other render engines. Can you show me some images, compared to Arnold? Thanks.

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I tried the vdb in max last night, looked fine. So its either Host related or settings.

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Ricardo Torres avatar image
Ricardo Torres answered ·

Thank you @Peter. Here is a frame of that same VDB sequence where we can see blockiness and the C4D project in case you want to look at the settings for the standard volume that I used. If you need more than one frame I can upload the rest too.

C4D R20 and C4DtoA 2.6.0 (Arnold 5.4.0.0)

Sorry about the bother during your vacation. Here is the link to DL:

https://www.dropbox.com/s/fmh7jx44rv8b3qm/VDB_test.zip?dl=0

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Ricardo Torres avatar image
Ricardo Torres answered ·

Here is a motion test I did of the same VBD seq. You definetaly see the blockiness in the emission but not in the density. Any ideas?

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Ricardo Torres avatar image
Ricardo Torres answered ·

I'm at a lost. Still can't get rid of this pixelation. @Peter Horvath any idea?


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